The heart of a computer is a magnetic hard disk drive (HDD) which typically includes a rotating magnetic disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected tracks on the rotating disk. The suspension arm biases the slider into contact with the surface of the disk when the disk is not rotating but, when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air bearing a slight distance from the surface of the rotating disk. When the slider rides on the air bearing the write and read heads are employed for writing magnetic impressions to and reading magnetic signal fields from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
The volume of information processing in the information age is increasing rapidly. In particular, it is desired that HDDs be able to store more information in their limited area and volume. A technical approach to meeting this desire is to increase the capacity by increasing the recording density of the HDD. To achieve higher recording density, further miniaturization of recording bits is effective, which in turn typically requires the design of smaller and smaller components.
The further miniaturization of the various components, however, presents its own set of challenges and obstacles, particularly for two dimension magnetic recording (TDMR) systems which require two or more sensors in the same head, e.g., MIMO heads. Signals received from the two or more sensors may then be processed to extract data encoded on a magnetic medium.
Several preexisting MIMO head designs include multiple sensors which are displaced in the down track direction. However, multiple sensors displaced in the track direction gives rise to significant alignment issues resulting from skew between the sensors and the corresponding tracks as misalignment and/or skew is compounded along the length of the displaced sensors. This causes positional tolerances and skew issues to become problematic. As a result, although the optimal sensor positioning is the cross-track direction for MIMO heads rather than having multiple sensors displaced in the track direction, it has previously been effectively unachievable.